A variety of newly machined metal and plastic parts must be cleaned during the manufacturing process to remove residues of oil, grease, penetrant and other materials. Typically total immersion systems convey parts through a series of cleaning stations that employ cleaning, agitating and spraying to dislodge chemicals and particles.
Parts to be washed are generally placed into containers and oriented based on the greatest number of parts per container dimensions without regard for other important factors such as penetrant removal. In a typical washing process turbulation moves solution over, under, around and through a part. Manifolds with jets or eductors direct a turbulent liquid flow over a working zone.
One of the functions of industrial parts washing is to remove penetrant used in inspection processes. Fluorescent penetrant inspection (FPI) is a widely applied method used to detect casting and forging defects, cracks, and leaks in new products, and fatigue cracks on in-service components surface breaking defects in non-porous materials such as metals, plastics, or ceramics. FPI is based upon fluid penetration into clean and dry surface-breaking discontinuities through capillary action. Penetrant may be applied to the test component by dipping, spraying, or brushing. After adequate penetration time has been allowed, the excess penetrant is removed and a developer is applied. The developer draws penetrant out of the flaw where an indication becomes visible to an inspector under various lighting conditions.
The effectiveness of the inspection depends on the removal of penetrant prior to application of the developer. The penetrant must be thoroughly removed except for that which reveals any defects in the parts. The contact points between the parts and the container are a problem for penetrant removal. Those part areas or points in contact with the container cannot be effectively spray rinsed without overwashing the non-contact surfaces.